1. Field of the Invention
This invention is concerned with isotope production by spallation reactions in selected targets by energetic protons, and consequently a broad spectrum of primarily neutron-deficient species is generated during the course of an irradiation. This invention discloses a novel method of separating and purifying .sup.82 Sr from irradiated Mo targets. Strontium-82 has a half life of 25 days and decays by pure electron capture to the ground state of its 75-second daughter, .sup.82 Rb. Rubidium-82 in turn decays, by 95% positron emission and 5% electron capture, to stable .sup.82 Kr and exhibits several prominent gamma rays. It is because such a shortlived alkali metal activity is available from a long-lived parent that the availability of .sup.82 Sr is of interest for biomedical studies. The useful shelf life of the system will be determined by the precursor activity, while the very short half life of .sup.82 Rb will keep the radiation dose to the patient low. With a suitable positron imaging device, this generator system appears to have considerable potential medical applications in cases where repeated, rapid, dynamic blood-flow information would be of value. Such instances would include investigations in coronary occlusion, cardiac output, arteriography, and tumor vascularity. A .sup.82 Rb generator could be a very effective diagnostic tool in the study of heart diseases.
2. Prior Art
To the inventors' knowledge, no one has previously used Mo targets to produce radiostrontium; consequently, such a complete and quantitative recovery of Sr from Mo is believed to be novel. Others have produced .sup.82 Sr with other targets and nuclear reactions, however. E.g., workers at the Donner Laboratory of the Lawrence Berkeley Laboratory irradiated Rb and Kr targets in the 88-in. cyclotron to produce .sup.82 Sr and then chemically purified it by ion exchange. Y. Yano and H. O. Anger, J. Nucl. Med. 9 412 (1968).